152 LABORATORY LESSONS IN GENERAL SCIENCE 



2. Into a piece of thin cotton cloth put a little bran, and 

 knead it in some water in an evaporating dish so long as any 

 milky liquid comes out through the cloth. Continue washing 

 it at the hydrant till the water runs off clear. State the 

 nature of what remains in the cloth, and of what has settled 

 in the dish. From which part of the wheat kernel does 

 each come? 



3. In like manner knead some flour in a cloth. When the 

 white solid has largely settled, pour off the water in the dish, 

 and spread some of the solid on a filter paper to dry by 

 evaporation. Crumble the dried solid later and state what 

 it resembles. 



Heat some of this solid with a little water in an evaporating 

 dish till the water boils. Wet a strip of filter paper in the 



FIG. 69. Effect of cooking upon starch granules. Cells of raw potato are 

 shown in a, and when cooked in b and c. 



solution, and let fall drops of iodine solution at different 

 spots on the paper. Note the characteristic blue of the test 

 for the presence of starch. 



4. In the same manner as in paragraph 4 under Eggs, test 

 some of the gluten (substance left in the cloth from the flour). 

 What is the result? 



